Influence of media composition on acid protease production by <i>Aspergillus niger</i> (NRRL 1785)

Abstract

Aspergillus niger (NRRL 1785) has been reported as a good producer of acid protease with optimum pH of 4.0 using glucose as the sole carbon source and peptone as sole nitrogen source. The production of acid protease by A.niger (NRRL 1785) using other carbon sources (lactose, sucrose, starch, maltose and glycerol) to substitute for glucose and other nitrogen sources (urea, casein, beef extract, groundnut meal and corn steep liquor) to substitute for peptone were studied. The effects of media composition on acid protease production were determined. All the fermentation media with different carbon and nitrogen sources tested supported acid protease production. Peak of enzyme production for all media composition was at the 96th hour of fermentation though at varying yields. Lactose supported the maximum production of 23.80 UmIi^-1 amongst the tested carbon source (glucose substitutes) while beef extract supported maximum protease production amongst peptone substitutes with protease activity of 19.95 UmI^-1. None of the media tested measured up to the protease activity of 26.05 UmI^-1. The result of this study gives a strong indication that A.niger (NRRL 1785) is capable of utilizing different carbon and nitrogen sources for acid protease production. Economically, this strain seems to be promising as an alternative microorganism for acid protease production.

Keywords: acid protease, Aspergillus niger (NRRL 1785), fermentation media

Global Journal of Pure and Applied Sciences Vol. 12(1) 2006: 85-88